1. Field of the Invention
This invention relates generally to gaskets for providing a seal between two components, and more particularly to multi-layer gaskets, such as cylinder head gaskets.
2. Related Art
Cylinder head gaskets, particularly multi-layered gaskets, are commonly used in vehicle engines. The gaskets form a seal between mating components of the engine, particularly around cylinder bores presenting combustion chamber openings, in order to prevent leakage of combustion gases and engine fluids. Cylinder head gaskets typically extend circumferentially around the cylinder bores and are positioned between an engine block and a cylinder head.
Such cylinder head gaskets are commonly formed of multiple layers of a metal material, such as stainless steel, and typically have one or more sealing beads spaced annularly around the combustion chamber opening, or another opening or edge, to facilitate a tight seal between the engine block and cylinder head. The multi-layered gaskets can also have a stopper for controlling compression or adjusting the load on the beads. The metal layers are typically coated with a coating material to assist in sealing the metal layers together and preventing fluid or gas leaks between the engine block and cylinder head. Without the coating material, a higher load would be necessary to seal the layers. The coating material also fills any imperfections in the surfaces of the layers.
It has been found, however, that such coating materials can cause instability between the cylinder head and engine block due to compression, recovery, and wear of the coating material. Over time, the coating material, which is not as hard or durable as the metal layers, can soften. The coating material can also extrude under high pressures causing misalignment.